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          <th colspan="3" align="center">DbEnv::set_event_notify()</th>
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            <h2 class="title" style="clear: both"><a id="envevent_notify"></a>DbEnv::set_event_notify()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;
 
int
DbEnv::set_event_notify(
    void (*db_event_fcn)(DB_ENV *dbenv, u_int32_t event, 
    void *event_info));</pre>
      <p>
         The <code class="methodname">DbEnv::set_event_notify()</code> method configures a callback function
         which is called to notify the process of specific Berkeley DB events.
    </p>
      <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
        <h3 class="title">Note</h3>
        <p>
                    Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for
                    example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work
                    correctly, and the results are undefined.
            </p>
      </div>
      <p>
         The <code class="methodname">DbEnv::set_event_notify()</code> method configures operations performed
         using the specified <a class="link" href="env.html" title="Chapter 5.  The DbEnv Handle">DbEnv</a>  handle, not all
         operations performed on the underlying database environment.
    </p>
      <p>
         The <code class="methodname">DbEnv::set_event_notify()</code> method may be called at any time
         during the life of the application.
    </p>
      <p>
         The <code class="methodname">DbEnv::set_event_notify()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="id1670100"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="id1670325"></a>db_event_fcn</h4>
              </div>
            </div>
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          <p>
                The <span class="bold"><strong>db_event_fcn</strong></span> parameter is the
                application's event notification function.  The function takes three
                parameters:
            </p>
          <div class="itemizedlist">
            <ul type="disc">
              <li>
                <p>
                        <code class="literal">dbenv</code>
                    </p>
                <p>
                        The <span class="bold"><strong>dbenv</strong></span> parameter is the enclosing
                        database environment handle.
                    </p>
              </li>
              <li>
                <p>
                                <code class="literal">event</code>
                    </p>
                <p>
                                The <span class="bold"><strong>event</strong></span> parameter is one of the
                                following values:
                    </p>
                <div class="itemizedlist">
                  <ul type="circle">
                    <li>
                      <p><a id="event_notify_DB_EVENT_PANIC"></a>
                            <code class="literal">DB_EVENT_PANIC</code>
                       </p>
                      <p>
                            Errors can occur in the Berkeley DB library where the only solution is
                            to shut down the application and run recovery (for example, if
                            Berkeley DB is unable to allocate heap memory).  In such cases, the
                            Berkeley DB methods will return 
                            <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_RUNRECOVERY" class="olink">DB_RUNRECOVERY</a>.
                            It is often easier to simply exit the application when such errors
                            occur rather than gracefully return up the stack.
                       </p>
                      <p>
                            When <span class="bold"><strong>event</strong></span> is set to DB_EVENT_PANIC,
                            the database environment has failed.  All threads of control in the
                            database environment should exit the environment, and recovery should
                            be run.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REG_ALIVE"></a>
					        <code class="literal">DB_EVENT_REG_ALIVE</code>
				        </p>
                      <p>
					        Recovery is needed in an environment where the 
                            <a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a> 
                            flag was specified on the 
                            <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method and there is 
					        a process attached to the environment.   The callback function is triggered
					        once for each process attached. 
				        </p>
                      <p>
					        The <span class="bold"><strong>event_info</strong></span> parameter points to a pid_t value 
					        containing the process identifier (pid) of the process the Berkeley DB library
					        detects is attached to the environment.   
				        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REG_PANIC"></a>
					        <code class="literal">DB_EVENT_REG_PANIC</code>
				        </p>
                      <p>
					        Recovery is needed in an environment where the
                            <a class="link" href="envopen.html#envopen_DB_REGISTER">DB_REGISTER</a>
                            flag was specified 
                            on the <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method.  All threads
					        of control in the database environment should exit the environment.   
				        </p>
                      <p>
                            This event is different than the <code class="literal">DB_EVENT_PANIC</code> event
                            because it can only be triggered when <code class="literal">DB_REGISTER</code> was
                            specified.   It can be used to distinguish between the case when a process
                            dies in the environment and recovery is initiated versus the case when an
                            error happened (for example, if Berkeley DB is unable to allocate heap
                            memory)
				        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_CLIENT"></a>
                            <code class="literal">DB_EVENT_REP_CLIENT</code>
                        </p>
                      <p>
                            The local site is now a replication client.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_ELECTED"></a>
                            <code class="literal">DB_EVENT_REP_ELECTED</code>
                        </p>
                      <p>
                            The local replication site has just won an election.  An application
                            using the Base replication API should arrange for a call to the 
                            <a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a>  method
                            after receiving this event, to reconfigure the local environment as a
                            replication master.
                        </p>
                      <p>
                            Replication Manager applications may safely ignore this event.  The
                            Replication Manager calls <a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a> 
                            automatically on behalf of the application when appropriate (resulting
                            in firing of the DB_EVENT_REP_MASTER event).
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_MASTER"></a>
                            <code class="literal">DB_EVENT_REP_MASTER</code>
                        </p>
                      <p>
                            The local site is now the master site of its replication group.  It is
                            the application's responsibility to begin acting as the master
                            environment.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_NEWMASTER"></a>
                        <code class="literal">DB_EVENT_REP_NEWMASTER</code>
                        </p>
                      <p>
                            The replication group of which this site is a member has just
                            established a new master; the local site is not the new master.  The
                            <span class="bold"><strong>event_info</strong></span> parameter points to an
                            integer containing the environment ID of the new master.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_PERM_FAILED"></a>
                            <code class="literal">DB_EVENT_REP_PERM_FAILED</code>
                        </p>
                      <p>
                            The replication manager did not receive enough acknowledgements (based
                            on the acknowledgement policy configured with 
                            <a class="xref" href="repmgrset_ack_policy.html" title="DbEnv::repmgr_set_ack_policy()">DbEnv::repmgr_set_ack_policy()</a> )
                            to ensure a transaction's durability within the replication group. 
                            The transaction will be flushed to the master's local disk storage for
                            durability.
                        </p>
                      <p>
                            The DB_EVENT_REP_PERM_FAILED event is provided only to applications
                            configured for the replication manager.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_REP_STARTUPDONE"></a>
                           <code class="literal">DB_EVENT_REP_STARTUPDONE</code>
                        </p>
                      <p>
                           The client has completed startup synchronization and is now processing
                           live log records received from the master.
                        </p>
                    </li>
                    <li>
                      <p><a id="event_notify_DB_EVENT_WRITE_FAILED"></a>
                           <code class="literal">DB_EVENT_WRITE_FAILED</code>
                        </p>
                      <p>
                            A Berkeley DB write to stable storage failed.
                        </p>
                    </li>
                  </ul>
                </div>
              </li>
              <li>
                <p>
                        <code class="literal">event_info</code>
                    </p>
                <p>
                        The <span class="bold"><strong>event_info</strong></span> parameter may
                        reference memory which contains additional information describing an
                        event.  By default, <span class="bold"><strong>event_info</strong></span> is
                        NULL; specific events may pass non-NULL values, in which case the
                        event will also describe the memory's structure.
                    </p>
              </li>
            </ul>
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      <div class="sect2" lang="en" xml:lang="en">
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            <div>
              <h3 class="title"><a id="id1670587"></a>Class</h3>
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        <p>
                <a class="link" href="env.html" title="Chapter 5.  The DbEnv Handle">DbEnv</a>  
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      <div class="sect2" lang="en" xml:lang="en">
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              <h3 class="title"><a id="id1670912"></a>See Also</h3>
            </div>
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        <p>
                     <a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a> 
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